• Transactions on Electrical and Electronic Materials
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• v.8 no.2
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• pp.84-88
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• 2007

[ $Bi_{1.5}Zn_{1.0}Nb_{1.5}O_7$ ] (BZN), $Bi_2Mg_{2/3}Nb_{4/3}O_7$ (BMN), and $Bi_2Cu_{2/3}Nb_{4/3}O_7$ (BCN) pyrochlore thin films were prepared on $Cu/Ti/SiO_2/Si$ substrates by pulsed laser deposition and the micro-structural and electrical properties were characterized for embedded capacitor applications. The BZN, BMN, and BCN films deposited at $25\;^{\circ}C$ and $150\;^{\circ}C$, respectively show smooth surface morphologies and dielectric constants of about $39\;{\sim}\;58$. The high dielectric loss of the films deposited at $150\;^{\circ}C$ compared with films deposited at $25\;^{\circ}C$ was attributed to the defects existing at interface between the films and copper electrode by an oxidation of copper bottom electrode. The leakage current densities and breakdown voltages in 200 nm thick-BMN and BZN films deposited at $150\;^{\circ}C$ are approximately $2.5\;{\times}\;10^{-8}\;A/cm^2$ at 3 V and above 10 V, respectively. Both BZN and BMN films are considered to be suitable materials for embedded capacitor applications.

• Transactions on Electrical and Electronic Materials
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• v.15 no.1
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• pp.24-27
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• 2014

In this study, the effects of Mn-doping and the electrode materials on the memory characteristics of $ZnO_xS_{1-x}$ resistive random access memory (ReRAM) devices on plastic are investigated. Compared with the undoped Al/$ZnO_xS_{1-x}$/Au and Al/$ZnO_xS_{1-x}$/Cu devices, the Mn-doped ones show a relatively higher ratio of the high resistance state (HRS) to low resistance state (LRS), and narrower resistance distributions in both states. For the $ZnO_xS_{1-x}$ devices with bottom electrodes of Cu, more stable conducting filament paths are formed near these electrodes, due to the relatively higher affinity of copper to sulfur, compared with the devices with bottom electrodes of Au, so that the distributions of the set and reset voltages get narrower. For the Al/$ZnO_xS_{1-x}$/Cu device, the ratio of the HRS to LRS is above $10^6$, and the memory characteristics are maintained for $10^4$ sec, which values are comparable to those of ReRAM devices on Si or glass substrates.

• Current Photovoltaic Research
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• v.3 no.1
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• pp.32-38
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• 2015

CIGS solar cell consisted of various films. In this research, we investigated electrode materials in $Cu(In,Ga)Se_2$ (CIGS) cells, including Al-doped ZnO (ZnO:Al), intrinsic ZnO (i-ZnO), and Al films. The sputtered ZnO:Al film with a sputtering power at 200W showed the lowest series resistance and highest cell efficiency. The electrical resistivity of the 200-W sputtered ZnO:Al film was $5.2{\times}10^{-4}{\Omega}{\cdot}cm$ by the rapid thermal annealing at $200^{\circ}C$ for 1 min. The electrical resistivity of i-ZnO was not measurable due to its high resistance. But the optical transmittance was highest with less oxygen supply and high efficiency cell was achieved with $O_2/(Ar+O_2)$ ratio was 1% due to the increase of short-circuit current. No significant change in the cell performance by inserting a Ni layer between Al and ZnO:Al films was observed.

• Journal of Powder Materials
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• v.26 no.5
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• pp.405-409
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• 2019

Piezoelectric ceramic specimens with the $Pb(Mg_{1/3}Nb_{2/3})_{0.65}Ti_{0.35}O_3$ (PMN-PT) composition are prepared by the solid state reaction method known as the "columbite precursor" method. Moreover, the effects of the $Li_2O-Bi_2O_3$ additive on the microstructure, crystal structure, and piezoelectric properties of sintered PMN-PT ceramic samples are investigated. The addition of $Li_2O-Bi_2O_3$ lowers the sintering temperature from $1,200^{\circ}C$ to $950^{\circ}C$. Moreover, with the addition of >5 wt.% additive, the crystal structure changes from tetragonal to rhombohedral. Notably, the sample with 3 wt.% additive exhibits excellent piezoelectric properties ($d_{33}=596pC/N$ and Kp = 57%) and a sintered density of $7.92g/cm^3$ after sintering at $950^{\circ}C$. In addition, the sample exhibits a curie temperature of $138.6^{\circ}C$ at 1 kHz. Finally, the compatibility of the sample with a Cu electrode is examined, because the energy-dispersive X-ray spectroscopy data indicate the absence of interdiffusion between Cu and the ceramic material.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.447-452
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• 2004

Vacuum interrupters in order to be used in various switch-gear components such as circuit breakers, distribution switches, contactors, etc. spread the arc uniformly over the surface of the contacts. The electrodes of vacuum interrupters are made of sinter-forged Cu-Cr materials for good electrical and mechanical characteristics. Since the closing velocity is 1-2m/s and impact deformation of the electrode depends on the strain rate at that velocity, the dynamic behavior of the sinter-forged Cu-Cr is a key to investigate the impact characteristics of the electrodes. The dynamic response of the material at intermediate strain rate is obtained from the high speed tensile test machine test and at the high strain rate is obtained from the split Hopkinson pressure bar test. Experimental results from both quasi-static and dynamic compressive tests are interpolated to construct the Johnson-Cook model as the constitutive relation that should be applied to simulation of the dynamic behavior of the electrodes. The impact characteristics of a vacuum interrupter are investigated with computer simulations by changing the amount of chromium content.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.112-115
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• 2004

Photovoltaic effects in $CuPc/C_{60}$ heterojunction structure have been studied depending on thickness of exciton blocking layer(BCP) and electrodes. Bare ITO and polymer coated electrode(PEDOT:PSS) were used as an anode, and Al, Ca/Al, Mg/Al, LiF/Al, and LiAl were used as a cathode. Photovoltaic parameters depending on BCP layer thickness from 0 to 60 nm and electrodes having different work function were measured using Keithley 236 source-measure unit and a 500W xenon lamp (ORIEL 66021). We have seen that the BCP layer thickness severely affects on the performance of photovoltaic cells.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1379-1381
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• 1998

Powder electroluminescent device (PELD) structured conventionally dielectric and phosphor layer, between electrode and their layer fabricated by screen printing splaying or spin coating method. To promote performance of PELDs, we approached the experiments for different structure and thickness variation of PELD. Thickness variation($30{\mu}m{\sim}130{\mu}m$) was taken. To investigate electrical and optical properties of PELDs, EL spectrum, transferred charge density using Sawyer-Tower's circuit brightness was measured. Variation of structure in PELDs was as follows: WK-1 (ITO/BaTiO3/ZnS:Cu/Silver paste), WK-2 (ITO/BaTiO3/ZnS:Cu/BaTiO3/ZnS:Silver paste), WK-3 (ITO/BaTiO3/ZnS:Cu/BaTiO3/Silver paste), WK-4(ITO/BaTiO3+ZnS:Cu/Silver paste) As a result, structure of the highest brightness appeared WK-4 possessed 60 ${\mu}m$ thickness. The brightness was 2719 cd/$m^2$ at 100V, 400Hz.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.12
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• pp.607-613
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• 2001

Molybdenum thin films were deposited on the soda lime glass(SLG) substrates by direct-current planar magnetron sputtering, with a sputtering power density of $4.44W/cm^2$. The working pressure was varied from 0.5 mtorr to 20 mtorr to gain a better understanding of the effect of sputtering pressure on the morphology and microstructure of the Mo film. Thin films of $CU(InGa)Se_2$ (CIGS) were deposited on the Mo-coated glass by three stage co-evaporation process. The highest efficiency device was obtained at the maximum value of the tensive stress. The morphology of Mo-coated films were examined by using scanning electron microscopy The film's microstructure, such as the preferred orientation, the full width at half-maximum(FWHM), and the residual intrinsic stress were examined by X-ray diffraction.

• Journal of Electrochemical Science and Technology
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• v.9 no.4
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• pp.276-281
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• 2018

High concentration of copper in mezcal, a representative Mexican spirituous alcoholic beverage, is a serious problem due to the damage that it may cause to human health. A cyclic voltammetry and square wave anodic stripping voltammetry study of copper (II) in three commercial mezcal samples based on glassy carbon electrode response was undertaken. The analysis was developed using a simulated matrix solution ($EtOH/H_2O$ (1:1), 0.1 M $LiClO_4$ and AcOH/AcONa 0.05 M/0.008 M), with Cu (II) concentrations in the range 0 - 1 ppm. Direct electrochemical analysis of mezcal samples was complicated by the presence of different organic compounds in the matrix. The analytical signal of Cu (II) in the spirituous was notably improved and the interferences caused by organic compounds were minimized, by diluting the mezcal samples 10% with $EtOH/H_2O$ (1:1) solution. An efficient quantification of Cu (II) was obtained from the calibration curve by the SWASV and using the internal standard method (Cd (II)) in commercial samples (1.2-6.7 ppm); the results were correlated satisfactorily with the values obtained by AAS.

• Journal of the Microelectronics and Packaging Society
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• v.7 no.4
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• pp.23-29
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• 2000

We demonstrate the fabrication method of high-density and high-quality solder bump solving a copper (Cu) cross-contamination in Si-LSI laboratory. The Cu cross-contamination is solved by separating solder-bump process by two steps. Former is via-formation process excluding Cu/Ti under ball metallurgy (UBM) layer sputtering in Si-LSI laboratory. Latter is electroplating process including Ti-adhesion and Cu-seed layers sputtering out of Si-LSI laboratory. Thick photoresist (PR) is achieved by a multiple coating method. After TiW/Al-electrode sputtering for electroplating and via formation in Si-LSI laboratory, Cu/Ti UBM layer is sputtered on sample. The Cu-seed layer on the PR is etched during Cu-electroplating with low-electroplating rate due to a difference in resistance of UBM layer between via bottom and PR. Therefore Cu-buffer layer can be electroplated selectively at the via bottom. After etching the Ti-adhesion layer on the PR, Sn/Pb solder layer with a composition of 60/40 is electroplated using a tin-lead electroplating bath with a metal stoichiometry of 60/40 (weight percent ratio). Scanning electron microscope image shows that the fabricated solder bump is high-uniformity and high-quality as well as symmetric mushroom shape. The solder bumps with even 40/60 $\mu\textrm{m}$ in diameter/pitch do not touch during electroplating and reflow procedures. The solder-bump process of high-uniformity and high-density with the Cu cross-contamination free in Si-LSI laboratory will be effective for electronic microwave application.